Exemplary embodiments of the invention generally relate to investment casting, and more particularly, to a core for forming a passage in an investment casting mold.
Investment casting is a commonly used technique for forming metallic components having complex shapes and geometries. especially hollow components such as those used in aerospace applications for example. The production of an investment cast part generally involves producing a ceramic casting mold having an outer ceramic shell with an inside surface corresponding to the shape of the part, and one or more ceramic cores positioned within the outer ceramic shell, corresponding to interior passages to be formed within the part. Molten alloy is introduced into the ceramic casting mold and is then allowed to cool and to harden. The outer ceramic shell and ceramic core(s) are then removed to reveal a cast part having a desired external shape and hollow interior passages in the shape of the ceramic core(s).
In comparison to other processes, for example sand casting or permanent mold casting, investment casting provides flexibility while maintaining tight tolerances. In particular, controlled solidification investment casting (CSIC) uses rapid directional cooling to enhance microstructure and mechanical properties. CSIC, therefore, may be useful for an expanded range of applications, particularly in the aerospace industry. However, investment casting is limited by the design of passages within the mold. Unlike a sand core used in a sand casting process, the ceramic cores used in CSIC are difficult to remove or destroy without affecting the molded part. As a result, the process of designing passages severely restricts the use of CSIC for applications requiring complex cored passages.